1. Field of the Invention
The present invention relates to a two hole, air assist type fuel injection device used in an internal combustion engine having two intake valves per cylinder.
2. Description of the Prior Art
Current internal combustion engines for automobiles tend toward a design having two intake valves, two exhaust valves, and an electronically controlled fuel injection devices per cylinder (a four valve EFI engine) for the purpose of realizing high response, minimizing air pollution, and improving fuel economy.
Japanese Utility Model Publication SHO No. 63-19874 (U.S. Pat. No. 4,982,716) proposes a fuel injection device for this type of engine having a fuel injection valve and an adapter coupled to the fuel injection valve. More particularly, the fuel injection valve has a fuel injection port for injection of fuel therethrough. The adapter has a concave portion defining a dead space therein, a fuel collision surface having a width larger than the diameter of the fuel injection port of the fuel injection valve and allowing the fuel from the fuel injection port to collide with the fuel collision surface to thereby change its flow direction, two branch port means formed on sides of the fuel collision surface for allowing the fuel to pass through the branch ports, and two air injection passages, opening to the dead space, for injecting air against the fuel above the fuel flow to promote atomization of the fuel.
However, in the fuel injection device having the fuel collision surface and the air injection ports, the atomization of fuel is greatly affected by the structure of the fuel injection device, for example, the sizes of the fuel collision surface and the fuel injection port and the angle of the air injection passages. Therefore, for the purpose of attaining a high grade of fuel atomization, an optimum structure should be developed.